The major goal of this research project is to examine pharmacologic interactions of adrenergic and cholinergic nervous systems in cat eyes. Changes in intraocular pressure, outflow facility and aqueous humor formation in response to drugs affecting adrenergic and cholinergic receptors and metabolism at specific sites will first be determined. The effectiveness of these agents after chronic lowering or elevation of adrenergic or cholinergic input to the anterior segment of the eye by surgical or pharmacological means will then be examined. Involvement of cyclic AMP as a mediator of the responses will be assessed by parallel measurement of levels of this nucleotide in aqueous humor. Basic mechanisms underlying the production of supersensitivity and subsensitivity will finally be explored in isolated iris sphincters and dilators with the use of physiological techniques.